Hermetic sealing is required to minimize influence of humidity and gas from outside, so as to improve performance and durability of electrical elements, such as, Organic Light Emitting Diode (OLED), Dye-sensitized solar cell (DSSC) or lighting (LED).
Especially, OLED becomes accepted as next generation display technology by its merits, such as, high response time, self-light-emitting with backlight unneeded, proper for manufacturing ultra-thin panel, low power consumption, and wide viewing angle.
Because OLED is susceptible to humidity and air, sealing is processed between upper and lower substrates to protect OLED device by blocking out humidity and air. In the process, glass frit paste is used as sealing agent.
Conventionally, as sealing material for OLED, frit glass such as V2O5-P2O5 has been used.
Especially, Korean patent publication 10-2010-0084476 by Hitachi discloses glass composition having low melting point which is produced by first step to prepare glass powder by melting V2O5, MnO, Fe2O3 in glass formulation and second step to mix low expansion ceramic powder with the glass powder.
And, Korean patent publication 10-2010-0049651 by Yamato discloses glass composition for adhesion which is produced by mixing low expansion ceramic powder with V2O5-BaO—ZnO glass.
The above production of glass composition includes steps to melt, cool down and pulverize glass, and to add certain amount of pulverized low expansion ceramic into glass powder to control thermal expansion coefficient.
However, thermal expansion coefficient of glass composition produced by the above method is significantly short of thermal expansion coefficient of frontal or posterior glass of OLED. In particular, difficulty of adhesion between frontal glass and metal is a problem.
In addition, to apply frit powder prepared as above on glass, processes to make the frit powder into paste using organic binder and then to burn out the binder at temperature of 400° C. are required. But, toxic substance is emitted during the processes.